The present invention relates to a device for dispensing an extrudable material.
A particular application of the invention lies in the field of dentistry, for dispensing pastes such as, for example, materials for making moldings, waxes for plugging purposes, composite resins or cements for tooth restoration treatments, or indeed insertion materials such as that described in French patent No. 89/07812, used to enlarge the gingival cleft.
More generally, the present invention can be used in other fields for extruding a variety of materials such as adhesives, cements, waxes, or elastomers.
The term "extrudable material" is used herein to designate any material which, unlike a liquid material, does not flow merely under the effect of gravity. Such materials can present a variety of viscosities. By way of example, the viscosity of the insertion material described in French patent No. 89/07812 to which the invention applies more particularly is between about 13,000 Pa.s and about 30,000Pa.s.
Numerous devices for dispensing extrudable material have been proposed in the state of the art, and in particular in the field of dentistry.
In general, such devices comprise a reservoir for containing said material to be extruded and for co-operating with piston-forming means that slide in said reservoir and that are suitable for enabling said material to be transferred into an endpiece extending said reservoir.
Two broad categories of dispenser device of the above type can be distinguished in the state of the art:
those in which the reservoir and the endpiece are constituted by a single part; and PA1 those in which the reservoir and the endpiece are constituted by two distinct elements. PA1 a reservoir designed to contain the material and having at least one orifice; PA1 a separable tubular endpiece communicating, in its in-use position, with said reservoir via said orifice; PA1 a piston suitable, in use, for sliding inside said reservoir and for exerting sufficient force on said material to cause it to be delivered to the outside via the endpiece; PA1 a base carrying means for controlling the displacement of said piston and including a plate-forming element disposed in a plane that is substantially orthogonal to the displacement direction of said piston, said plate having a passage suitable for receiving said endpiece and being disposed facing the orifice of said reservoir; PA1 a sealing piece having an orifice extending the passage through said plate; PA1 means for making a sealed connection between said endpiece and said sealing piece, at least under the effect of said reservoir being displaced towards said plate; and PA1 means for preventing said sealing piece from moving relative to said plate, at least under the effect of the displacement of said reservoir towards said plate; PA1 the device being characterised in that said sealing piece has a sealing face facing towards said reservoir; said sealing face and the wall defining the orifice being suitable:
The present invention relates more particularly to a device belonging to the second category.
When designing a device belonging to said second category, the main problem that needs to be solved is naturally that of sealing between the endpiece and the reservoir, in particular during the stage in which the material is being delivered.
To solve this technical problem, presently-known devices make use of more or less elaborate mechanical fastenings between the endpiece and the reservoir, for example a screw fastening or a bayonet type fastening.
Such devices are described in particular in patents U.S. Pat. No. 3,121,516 and U.S. Pat. No. 3,767,085.
Although they provide a satisfactory solution to the problem of sealing between the endpiece and the reservoir, those known devices are often fragile, presenting a shape that is complex and easily clogged with the extruded substance, and difficult to clean. They are relatively awkward to use when changing the endpiece or the reservoir.
Also known in the state of the art, and in particular in the field of dentistry, are devices for injecting liquid, in particular hypodermically, said devices comprising a reservoir and a separable endpiece.
Such devices are described, for example, in documents BE 515,066, FR 2,245,382, FR 1,320,820, U.S. Pat. No. 1,818,670.
In those known devices, the reservoir containing the liquid to be injected is generally constituted by a glass bulb, and has an orifice which is closed by a plug, optionally a perforatable plug, which is made of an elastomeric material.
The plug has a central orifice in which said endpiece can be engaged as a force-fit with friction.
Sealing between the endpiece and the reservoir containing the liquid to be injected is consequently provided by co-operation between two cylindrical surfaces which are tightly pressed together by radial clamping, one of the surfaces also being elastically deformable.
In addition to be unsuitable for dispensing extrudable materials, those known devices suffer from the drawback of leading to the endpiece becoming mechanically secured to the reservoir, with the endpiece being separable from said reservoir only under the effect of an outside force that is relatively large.
Furthermore, since the reservoir is made of glass, it is particularly fragile and can under no circumstances be used for dispensing an extrudable material.